edX

edX presents the most academically faithful interface here, mirroring an actual university LMS down to the structure. Courses break into a sequence navigator: a horizontal ribbon of units you click through, each holding a video, a reading, or a problem set, nested under collapsible sections in a course outline. The problem components support genuinely varied types, from math expressions to code graders, reflecting its roots in higher-ed coursework. Progress and grades are tracked against weighted deadlines like a real class. The cost of that fidelity is interface density; the navigation can be fiddly, with the unit ribbon and outline sometimes competing, and the catalog's mix of free auditing, verified certificates, and full programs makes it hard to tell at a glance what any given enrollment commits you to.